Biochemistry Review

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1. Although most large molecules (macromolecules) may appear
complex they are often polymers -- that
is composed of many identical small molecules (monomers).

2. The empirical formula for many carbohydrates may be written
(CH2O)n.

3. The simplest common carbohydrates have a
three carbon backbone so their formula
would be (CH2O)3.

4. Single sugars are called
monosaccharides.

5. The next level of saccharide complexity involves two sugars
linked together. They are represented by the
disaccahride sucrose--table sugar.

6. A chain of many monosaccharides linked together is called a
polysaccharide.

7. Monosaccharides may occur in a chain or a ring, and nearly
every carbon will have a(n) hydroxyl
(-OH) functional group attached as well as a hydrogen.

8. One of the end-carbons in most monosaccharides forms a double
bond with oxygen producing an aldehyde
group.

9. When a carbon within a chain has a double bond with an oxygen
atom it is called a ketone.

10. The shape of simple sugar subunits in polysaccharides like
amylose is a ring.

11.The most common and most important monosaccharide is dextrose
or D glucose (an aldehyde).

12. Dextrose plays important roles in energy metabolism,
photosynthesis, and as a subunit
(monomer) for many complex carbohydrates.

13. In order to link two sugar molecules an oxygen bridge is
formed between two monosaccharides. In the process a water molecule
is liberated (dehydration). The bond between to adjacent sugar
subunits is called aglycosidiclinkage.

14. Most chemical reactions in the body such as the dehydration
synthesis described above require the presence of special proteins
called enzymes.

15. Most metabolic reactions are not spontaneous and must have a
source of energy in order to go to completion. This energy source is
typically a molecule of ATP.

16. The open chain sugar molecule has two ends; an aldehyde or a
ketone end and a glyceride or repeating hydroxyl end. From which end
of a sugar molecule should you begin numbering the carbon atoms?
The aldehyde or ketone end.

17. When a sucrose molecule (glucose-fructose) enters your
gastrointestinal tract it will be broken down by a process called
hydrolitic cleavage (during which water
is added by an enzyme).

18. Lactose like sucrose is a
disaccharide found only in milk. This sugar is digested by infants
but cannot be tolerated by most adults because they lack the enzyme
necessary split it in two.

19. Two basic purposes of polysaccharides are food storage and
structural properties.

20. Polysaccharides used for food storage are amylose or
amylopectin (plants) and glycogen
(animals)

21. The polysaccharide cellulose is found mostly in
plant cells and several algae.

22. Chitin is used by arthropods (insects, spiders etc.) to form a
tough exoskeleton.

23. All plant starches such as
amylose and amylopectin are made almost
exclusively of glucose subunits.

24. Amylose is the simplest starch--glucose molecules joined by
1-4 alpha linkages--whereas amylopectin
is a highly branched polymer.

25. Amylose can become insoluble in water because it will
spontaneously form a(n) helix --the
secondary structure of the molecule--a shape formed by hydrogen
bonding between the sugar subunits rather than with water.

26. Animal starch or glycogen provides temporary energy storage
which is concentrated in muscle cells
and the liver of vertebrates.

27. Glycogen is larger than amylopectin and more complex because
its branches have their own
branches.

28. Iodine is a substance can be used
to easily identify starch because it forms a dark blue complex

*While both amylose and cellulose are formed by 1-4 dehydration
linkages between glucose molecules they have vastly different
properties. You should be able to describe the functional
differences between these two polymers.

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29. The structural difference between cellulose and starch is
based on the location of the hydroxyl group found on carbon-one of
the glucose ring. As the 1-4
beta-linkages of cellulose form, every other monomer in the chain is
turned over.

30. Only a few organisms have evolved an efficient enzyme,
cellulase, necessary to break the
beta-glycosidic linkage found in cellulose.

31. Termites and grazing animals are able to digest the cellulose
in the plants they eat because of a symbiotic relationship with
certain intestinalmicroorganisms.

* You should be able to describe the microscopic details of plant
cell walls which make them one of the strongest of biological
structures. Your description should include such terms as beta
glycoside linkages, microfibrils, fibrils, and laminated cell wall
structure.

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33. Arthropods and fungi have evolved a structural polysaccharide
called chitin which is made up of
N&emdash;acetylglucosamine subunits.

34. Special polysaccharides complexed with protein form much of
the jellylike substance that fills the
eye and lubricating fluids of skeletal
joints. Heparin is one such proteoglycan which has the vital role of
inhibiting the clotting of blood.